Braille is used by blind and visually impaired individuals as a means of reading and writing text, and a wide range of devices and systems are available for these purposes. These include Braille writers and readers for use either as stand-alone units or in communication with other electronic devices such as, for example, personal computers, tablet computers, smartphones, personal digital assistants, and the like.
Over the last decade, many blind and visually impaired individuals have started using portable Braille devices, also known as notetakers, which include input and output interfaces for respectively entering and displaying Braille content. The input interface is typically embodied by a Perkins-style Braille keyboard. The output interface is often a refreshable Braille display consisting of one or several rows of Braille cells located adjacent the Braille keyboard. Each cell typically includes a plurality of electromechanically controlled pins or dots which can be selectively moved up and down to enable tactile Braille reading. In addition to being useful for typing and displaying Braille content, some notetakers can function as portable computers with software intelligence and processing capabilities that allow performing many functions such as, for example, e-mail and Internet access, data storage, book reading, calendar and contact information management, and connectivity to peripheral devices such as personal computers, tablet computers, smartphones, cellular phones, keyboards, monitors, printers, embossers, hard and flash drives, a camera, and the like.
Due to the widespread use of tablet computers and smartphones in recent years, Braille notetakers have faced intense competition from these lightweight, versatile and ergonomically designed mobile devices. For instance, many of these devices now offer Braille mobile applications targeting the communication needs of blind and visually impaired individuals, including software-generated virtual keyboards having Perkins-style Braille keyboard layout for implementation on a touch screen. Such virtual Braille keyboard implementations need to be calibrated to be operated efficiently.
However, a touch screen is generally not provided with tactile references for enabling a user to assess the location of the keys on a virtual keyboard implemented on the touch screen. As such, it is often unavoidable for a user's fingers to inadvertently drift off the key locations over time during typing. Visually impaired users, however, may not be aware of such a drift as they cannot simply look down at the virtual keyboard to ensure that each of their fingers is adequately positioned with respect to the associated virtual key. Additionally, touch screens adapted for Braille typing may not always be provided with a visual display. In some scenarios, a user could also wish to voluntary change the positions of a number of his or her fingers on the touch screen while typing, but without having to expressly perform a full recalibration of the virtual Braille keyboard. Accordingly, various challenges still exist in the implementation and calibration of virtual Braille keyboards.